Tens of millions of network-enabled devices including routers, printers, media servers, IP cameras, smart TVs and more can be attacked over the Internet because of dangerous flaws in their implementation of the UPnP (Universal Plug and Play) protocol standard, security researchers from Rapid7 said Tuesday in a research paper.

UPnP allows networked devices to discover each other and automatically establish working configurations that enable data sharing, media streaming, media playback control and other services. In one common scenario a file-sharing application running on a computer can tell a router via UPnP to open a specific port and map it to the computer's local network address in order to open its file-sharing service to Internet users.

UPnP is intended to be used primarily inside local networks. However, security researchers from Rapid7 found over 80 million unique public IP (Internet Protocol) addresses that responded to UPnP discovery requests over the Internet, during scans performed last year from June to November.

Furthermore, they found that 20 percent, or 17 million, of those IP addresses corresponded to devices that were exposing the UPnP SOAP (Simple Object Access Protocol) service to the Internet. This service can allow attackers to target systems behind the firewall and exposes sensitive information about them, the Rapid7 researchers said.

Based on the UPnP discovery responses the researchers were able to fingerprint unique devices and discover what UPnP library they were using. They found that over a quarter of them had UPnP implemented through a library called the Portable UPnP SDK.

Eight remotely exploitable vulnerabilities have been identified in the Portable UPnP SDK, including two that can be used for remote code execution, the researchers said.

"The vulnerabilities we identified in the Portable UPnP SDK have been fixed as of version 1.6.18 (released today), but it will take a long time before each of the application and device vendors incorporate this patch into their products," HD Moore, chief security officer at Rapid7, said Tuesday in a blog post.

Over 23 million IP addresses from those identified during the scans corresponded to devices that can be compromised through the Portable UPnP SDK vulnerabilities by sending a single specifically crafted UDP packet to them, according to Moore.

Additional vulnerabilities, including ones that can be used in denial of service and remote code execution attacks, also exist in a UPnP library called MiniUPnP. Even though these vulnerabilities have been addressed in MiniUPnP versions released in 2008 and 2009, 14 percent of the Internet-exposed UPnP devices were using the vulnerable MiniUPnP 1.0 version, the Rapid7 researchers said.

Other issues have been identified in the latest version of MiniUPnP, 1.4, but they won't be publicly disclosed until the library's developer releases a patch to address them, they said.

"All told, we were able to identify over 6,900 product versions that were vulnerable through UPnP," Moore said. "This list encompasses over 1,500 vendors and only took into account devices that exposed the UPnP SOAP service to the Internet, a serious vulnerability in and of itself."

Belkin, Cisco, Netgear, D-Link and Asus, which all have vulnerable devices according to lists published by Rapid7, did not immediately respond to requests for comment sent Monday.

Moore believes that in most cases networked devices that are no longer being sold will not be updated and will remain exposed to remote attacks indefinitely unless their owners manually disable the UPnP functionality or replace them.

"These findings prove that too many vendors still haven't learned the basics of designing devices that default to a secure and robust configuration," said Thomas Kristensen, chief security officer at vulnerability research and management firm Secunia. "Devices that are intended for direct Internet connections should not run any services on their public interfaces by default, particularly not services like UPnP, which are solely intended for local 'trusted' networks."

Kristensen believes that many of the vulnerable devices are likely to remain unpatched until they are replaced, even if their manufacturers release firmware updates.

Many PC users don't even update PC software that they frequently use and are familiar with, he said. The task of finding the Web interface of a vulnerable networked device, obtaining the firmware update and going through the whole update process will likely be too intimidating for many users, he said.

The Rapid7 research paper includes security recommendations for Internet service providers, businesses and home users.

ISPs were advised to push configuration updates or firmware updates to subscriber devices in order to disable UPnP capabilities or to replace those devices with others that are configured in a secure manner and don't expose UPnP to the Internet.

"Home and mobile PC users should ensure that the UPnP function on their home routers and mobile broadband devices has been disabled," the researchers said.

In addition to making sure that no external-facing device exposes UPnP to the Internet, companies were advised to perform a careful review of the potential security impact of all UPnP-capable devices found on their networks -- networked printers, IP cameras, storage systems, etcetera -- and consider segmenting them from the internal network until a firmware update is available from the manufacturer.

Rapid7 released a free tool called ScanNow for Universal Plug and Play, as well as a module for the Metasploit penetration testing framework, that can be used to detect vulnerable UPnP services running inside a network.

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